Becker M

Characterization of two human mammary carcinomas, MT-1 and MT-3, suitable for in vivo testing of ether lipids and their derivatives

SummaryThe human mammary carcinomas MT-1 and MT-3 originate from surgical material and were transplanted in nude mice. Both tumors have been classified as estradiol- and progesterone receptor-negative. Therapeutic doses of hormones and anti-hormones remained without growth inhibitory effect. MT-1 and MT-3 proved to be sensitive to conventional cytostatic drugs used for treatment of mammary carcinomas; striking is their sensitivity to ether lipids. Therefore, they are considered suitable tumor models for this class of substances.

Antileukaemic activity of treosulfan in xenografted human acute lymphoblastic leukaemias (ALL).

Treosulfan (L-threitol-1,4-bis-methanesulphonate; Ovastat(R)) is a bifunctional alkylating drug indicated for the treatment of advanced ovarian carcinoma. Recent data revealed immunosuppressive characteristics and substantial haematopoietic stem cell toxicity after repeated dosing of mice. Therefore, treosulfan is considered to be an alternative conditioning agent to busulfan (for example) administered prior to allogeneic/autologous stem cell transplantation of patients with haematological malignancies. An antineoplastic activity for treosulfan has been previously shown in preclinical models of melanoma, breast, lung and renal-cell carcinomas. Here, in vivo antileukaemic activity of treosulfan is compared with the activity of equitoxic doses of cyclophosphamide or busulfan for the first time using human acute lymphoblastic leukaemia (ALL)-models of paediatric origin xenotransplanted into non-obese diabetic (NOD)/severe combined immunodeficient (SCID) mice. Treosulfan treatment achieved an optimum treated to control (T/C) value of 159% (survival time) against B-ALL-SCID 7 and a T/C value of 0% (tumour growth) against T-ALL-SCID 4 and proB-ALL-SCID 19, respectively. Complete regression of established subcutaneously (s.c.) growing nodules of ALL-SCID 4 and 19 was obvious and long-term survivors without tumour re-growth were observed. Equitoxic doses of busulfan (ALL-SCID 4, 7, 19) or cyclophosphamide (ALL-SCID 19) were less effective with regard to the numbers of complete regressions and the number of cured animals. Side-effects included myelotoxicity and a small reduction in body weight, but these were tolerable. Treosulfan can be considered a highly active antileukaemic drug whose corresponding clinical value is to be tested in appropriate protocols with leukaemic patients.

Anti-proliferative efficacy of icariin on HepG2 hepatoma and its possible mechanism of action.

The aim of the present work was to explore the anti-hepatoma effects of icariin both in vitro and in vivo and to elucidate its potential mechanism of action. The MTT assay was applied to test the anti-proliferative effects of icariin in vitro. HepG2 bearing NMRI nu/nu mice were used to test the anticancer effects of icariin in vivo. Immunohistochemical assay and flow cytometry assay (FACS) were applied to detect the possible mechanisms of action of icariin. MTT assay illustrated that icariin inhibited the proliferation of HepG2 cells in a concentration dependent manner; meanwhile, icariin inhibited the tumor growth in HepG2 bearing NMRI nu/nu mice. The tumor weight was inhibited by 55.6% and tumor volume was inhibited by 47.2%. Icariin did not influence the spleen and body weights or blood parameters. Immunohistochemical analysis indicated that the expressions of both CD31 and Ki67 in the icariin treated group were significantly lower than those in the control group (p < 0.01). FACS assay showed that icariin dramatically decreased the percentage of CD4+ and CD8+ cells in bone marrow and CD19+ cells in blood on day 8. On day 17, the percentage of CD8+ cells in blood was lower than those in the control group. CD4/CD8 ratio in icariin group was significantly elevated in bone marrow on day 17. Icariin showed anticancer efficacy both in vitro and in vivo. The possible mechanism of action could be related to its anti-angiogenesis and anti-proliferative effects in tumors.

Development and characterization of a tamoxifen-resistant breast carcinoma xenograft

A human tamoxifen-resistant mammary carcinoma, MaCa 3366/TAM, originating from a sensitive parental xenograft 3366 was successfully established by treatment of tumour-bearing nude mice with 1–50 mg kg–1 tamoxifen for 3 years during routine passaging. Both tumours did not differ significantly in OR- and PR-positivity, however, when compared with the sensitive tumour line, the mean OR content of the TAM-resistant subline is slightly lower. An OR-upregulation following withdrawal of oestradiol treatment was observed in the parental tumours but not in the resistant xenografts. Following long-term treatment with tamoxifen, the histological pattern of the breast carcinoma changed. The more differentiated structures being apparent after treatment with 17β-oestradiol in the original 3366 tumour were not induced in the resistant line. Tamoxifen failed to induce a tumour growth inhibition in comparison to the tamoxifen-sensitive line. The pure anti-oestrogen, ICI 182 780, revealed cross-resistance. Sequence analysis of the hormone-binding domain of the OR of both lines showed no differences, suggesting that either mutations in other regions of the OR are involved in the TAM-resistance phenotype or that mechanisms outside of this protein induced this phenotype. Oestrogen and anti-oestrogen regulate pS2 and cathepsin D expression in 3366 tumours as in the human breast cancer cell line MCF-7. The resistant 3366/TAM tumours have lost this regulation. The established breast cancer xenografts 3366 and 3366/TAM offer the possibility of investigating mechanisms of anti-oestrogen resistance in an in vivo situation. They can be used to test novel approaches to prevent, or to overcome, this resistance in a clinically related manner.

EFFECTS OF AMIFOSTINE (WR-2721, ETHYOL) ON TUMOR GROWTH AND PHARMACOLOGY OF CYTOTOXIC DRUGS IN HUMAN XENOTRANSPLANTED NEUROBLASTOMAS

Amifostine was developed as a radio- and chemoprotective agent. It has shown protection against whole-body irradiation, and myelo- and nephrotoxicity of cytotoxic agents both in experimental and clinical studies. Some experimental trials revealed an influence of amifostine on tumor growth or the activity of cytotoxic drugs under certain circumstances. Therefore, it was the aim of our work to evaluate the pharmacological potential of amifostine in a preclinical in vivo situation with human xenotransplanted neuroblastomas. Human neuroblastoma cells (IMR5-75 and Kelly) were grown s.c. as xenografts in nude mice to palpable sizes (approximately 4 x 5 mm). Then the animals received 200 mg/kg amifostine i.p. and were treated 30 min later with one of the following cytotoxic drugs: cyclophosphamide, doxorubicin, cisplatin, ifosfamide, vincristine and etoposide. Amifostine as the only treatment did not influence the growth of the neuroblastomas IMR5-75 and Kelly. We observed no side effects of the compound itself. In no case did amifostine interact significantly with the antitumor effect of any cytostatic used in combination. However, amifostine mitigated the body weight loss induced by vicristine and the leukopenia induced by cyclophosphamide, cisplatin or ifosfamide, respectively. The side effects of the remaining cytostatics were--if observed at all--unchanged. We conclude that amifostine did not influence the tumor growth of xenotransplanted neuroblastomas and did not reduce the antineoplastic activity of the tested cytostatic drugs. Further investigation of amifostine as a protectant from side effects of chemotherapy in a clinical setting is warranted.

Stimulation of Hematopoiesis by Carboplatin-Liposomes

AbstractFollowing a single intravenous (i.v.) injection of carboplatin-liposomes (REV, HEPC:CH 1: 0.25) into mice peripheral white blood cell (WBC) counts increase to more than 30 000 × 106/ml. This elevation is observed between the 14th and 30th day after administration and significantly higher than normal values are registered even at day 42. Differentiation of WBC reveals both an increase of granulocytes, lymphocytes and monocytes. In parallel, platelets and erythrocytes are reduced moderately. Free carboplatin, empty liposomes or cis-platin-liposomes never caused a similar pharmacological behavior. This increase in peripheral WBC counts is accompanied by a distinct reduction of cell counts in spleens and bone marrow of the same mice. We suppose that carboplatin-liposomes (CPL) are taken up by monocytes/macrophages as their natural target. Within these cells cytokines are induced and released which secondarily lead to an induction of haematopoietic growth factors. This hypothesis is strengthened by the...

Differences in immunoreactivity of estrogen receptor (ER) in tamoxifen-sensitive and -resistant breast carcinomas: preclinical and first clinical investigations

Inherited or acquired tamoxifen resistance is a major constraint in the endocrinological treatment of breast carcinomas. We developed an enzyme-immunoassay that discriminates between tamoxifen-sensitive and -resistant tumors. The procedure was established and standardized using two xenografted breast carcinomas – 3366 (highly sensitive to tamoxifen) and 3366/TAM (acquired tamoxifen resistance). The latter model was developed by treatment of 3366 tumor-bearing nude mice during serial passaging over 3 years with tamoxifen. Both lines were estrogen receptor (ER) positive (101 or 82 fmol/mg protein), and revealed no differences in the nucleotide sequences of the hormone binding domain of the ER protein. However, while in the sensitive tumors an upregulation of ER levels was registered after estradiol treatment of tumor bearing nude mice, the ER expression in the resistant line remained unchanged. The tamoxifen sensitive and -resistant breast carcinoma 3366 differed, additionally, in their immunoreactivity of ER to mAB H222. While an incubation with estradiol or tamoxifen of immobilized ER prepared from cytosols of the sensitive tumors 3366 led to a significant increase in immunoreactivity, samples of resistant tumors failed in the exposition of additional immunologically reactive epitopes. These results were the basis for the development of an assay for determination of the tamoxifen response in patients. Our retrospective results with 38 breast tumors from a tumor bank indicated that patients with an increase of immunoreactivity of ER more rarely had a recurrence while under going tamoxifen therapy compared with patients expecting no increase. However, the data indicate interesting changes occurring with the ER of tam-resistant tumors that are to be explained by further mutational or protein-chemical analysis.